Please help to locate oil leak
 

Hi everyone:
For the last few months, after driving my X5 for about 30 min, i can smell an oil burning odor somewhere under the hood... From searching and readings, many posts mentioned about leaks around the valve cover gasket so I tried to look for signs of leak around the valve cover but I did not find any. In fact, I used paper towel to check around the valve cover' front, back, and sides but they are clean and bone dry. I then looked under the car, passenger side, and saw a wide patch of dry oil burn residues on the underside cover of one of the catalytic converters (the inside one - closer to the engine). From the catalytic looking directly up, everything is clean and dry from this side of the engine, the 2 x 3 into 1 headers are also dry. Assuming an oil leak should drip down from a location above it due to gravity, where could it came from? I concern that this problem could be a major repair...
2005 X5 3.0: Auto.

It sure sounds like a valve cover leak...Its not a matter of if the VC will leak, but when.

I'd take that paper towel and double check the area above the exhaust manifold/ heat shields in the passenger side rear corner of the valve cover.

Other common sources of an oil leak on this engine are:
-the Oil Filter housing gasket - which is behind/below the alternator on the engine
-Oil level sending unit - bottom of oil pan
-Oil Pan gasket.

Effduration has you looking in the right direction.

I recently chased down an oil leak and did VCG's first. Found out it was OFHG (oil filter housing gasket). Now, I have a 4.4 V8, so your application may be different, but like Eff said, those are good places to start at. Good luck!:thumbup:

i just had the same problem underneath intake manifold(while doing my valley pan and water pump) there's two oil hoses that dry rot and leak willing to bet thats it

I have a 3.0 also. I just redid my valve cover gasket. I would get the same symptoms as you. The primary leaks were at the interior bolts for the valve cover. The ones that run down the middle of the valve cover. It seems like when the oil built up in the interior of the top it would run out and onto the heat shield above the exhaust manifolds and burn or cook off. Judging from the oil there I had to clean off. No smoke just the smell of of hot almost burning oil. The gasket on the outside of the valve cover wasn't leaking.

I feel your pain. After I drove my car for a couple of hours, it would starts smelling and then at some point the smoke would come through the vents. This was after I changed the valve cover gasket. It smelled like plastic.
One thing I noticed when I changed it, is that the previous owner has changed it not long ago.
I opened the hood, and the burning was coming from passenger side under the hood, somewhere below the heat shields.
I noticed the grommets deteriorated to the point of crumbling and falling apart. So I ordered new grommets and installed them.
Didn't drive the car yet as I'm doing a major overhaul under the hood.
Hopefully when I drive it next time it won't happen again.

Hmmm, i checked the valve cover for leaks a couple of times already. I even removed the two plastic cover pieces on the top so that I can properly reach and touch all the corners and sides of the VC (especially the back sides)...but I will check again. The mysterious part was that, if the valve cover leaked (as you all and I suspected in the far left back location), how come nothing showed up when i checked it with a white paper towel?

Because it may be leaking from where mine was. The grommets at the interior/middle of the valve cover. When I changed out my valve cover gasket I did all of the gaskets and the grommets. The grommets were hard as a rock and would snap in two when flexed. The gasket at the spark plug ports was the same.

Oil leak or oil burning smell? One drop burns, a flood drips over night!

Note all six bangers need a valve cover gasket replacement (RESEAL) every 60-80K. If it has not been done in your ownership, just do it. And while you have your head in there, look at all the other items that need doing:
as posted before:
Oil filter housing gasket
Vanos oil line
Oil Separator and hoses (don't forget the intake parts too!)

See the DIY Articles on this list and you will see they are a VERY common list that fail/leak/etc

Thanks everyone for helping! Since the job is not too hard, I will do a gasket reseal with new grommets to see if the oil burning odor goes away. Yes, the burning smell is a pain in the neck. BTW, i did a VC gasket reseal like 3 years ago (but reused old grommets) because it was obviously leaked back then. I probably got 28K-30K since the first reseal.